BIOL 2710 Exam 2

CNS

brain and spinal cord

PNS

nerve tissues that have any part lying outside of the CNS

what do cranial and spinal nerves refer to?

points of origin

how are afferent and efferent divisions separated?

by direction of information flow

what does afferent or sensory refer to?

all incoming signals (somatic sensory and autonomic sensory) pathways

what does efferent or motor refer to?

all outgoing signals (somatic motor or autonomic motor)

somatic nervous system

composed of the somatic motor division and the somatic sensory division

somatic motor division

carries information from the CNS to the somatic effectors or skeletal muscles, voluntary system

somatic sensory division

carries information from the somatic effectors (muscles) and special receptors (sensation}) to CNS

autonomic nervous system- efferent

parasympathetic and sympathetic divisions carry information to the autonomic or visceral effectors (smooth muscles, cardiac muscle, glands), involuntary system

autonomic nervous system- afferent

visceral (organ) sensory division carries information back to CNS from visceral receptors

what are the two main types of cells in the nervous system?

neurons and glia or glial cells

neurons

excitable cells that conduct impulses and lose the capacity for cell division

glia or glial cells

cells that support neurons in some way and retain the capacity for cell division

astrocytes

a type of glial cell in the CNS, largest of glia, star shaped, most numerous of glia, and forms blood brain barrier with endothelial cells of capillaries

oligodendrocytes

a type of glial cell in CNS, generates the myelin sheath around nerve fibers in the CNS, the processes of oligodendrocytes do this rather than the entire cell body

schwann cells

a type of glial cell, generates the myelin sheath in the PNS, wrap around white nerve fibers in the PNS to myelinate them, cell membranes loaded with phospholipid myelin wrap around and insulate the cell, nuclei and cytoplasm are forced to exterior and form the neurilemma

what is neurilemma essential for?

regeneration of injured nerve fibers

unmyelinated Nodes of Ranvier are _________ between cells

spaces

what are the three components of neurons?

cell body or perikaryon, dendrites, and axon

what are also called nerve fibers?

dendrites and axons

cell body of neurons

nucleus, organelles, mitochondria replicate here, all proteins, carbohydrates, lipids, and nucleic acids are made here, including neurotransmitters and molecules needed for the maintenance of the cell, nissel bodies

nissel bodies

dense arrangements of rough ER for protein synthesis

dendrites

branches of the cell body that receive signals and transmit them to the main part of the cell body, may receive stimuli from the axon or axons of one or many other neurons, may receive stimuli from external environment

axon

neurons have only one, comes off of a narrowing of the cell body called the axon hillock, may have main branches called collaterals, and end in small branches called telodendria that terminate in synaptic knobs

nerve signals travel down the axon _____ from the cell body.

away

input zone- dendrites and cell body

receptors on dendrites and cell body respond to chemical, mechanical, environmental, or other stimuli, touch and stretch receptors are mechanical, neurotransmitters are chemical, heat and cold are environemental

summation zone- axon hillock

signals from all the dendrites and cell body are summed to determine if neuron will send a signal

conduction zone- axon

signal transduction in the axon is unidirectional from cell body to end of axon, and it is an all or nothing response

output zone- telodendria and synaptic knobs

neurotransmitter will be released to stimulate or inhibit the target of the neuron (muscles, glands, other neurons)

what neurons carry the signal from the central nervous system to the effectors (muscles and glands)?

efferent or motor neurons

what transfers signals from one neuron to the next in the central nervous system?

associative or interneurons